JP2909248B2 - Boron nitride coated member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boron nitride coated member having a cubic boron nitride film applied to a cutting tool or the like or a hard boron nitride film containing cubic boron nitride.

[0002]

2. Description of the Related Art Cubic Boron Nitride
CBN) is known as an excellent wear-resistant material because it has hardness next to diamond and low reactivity. Conventionally, this CBN can only be produced by a high-temperature and high-pressure method, and only a granular CBN can be synthesized. Therefore, its use range has been limited to sintered products and abrasive grains. So, to expand the range of use,
A method of synthesizing CBN as a film has been studied, and PVD (physical vapor deposition) using ions, plasma C
Synthesis by the VD (chemical vapor deposition) method has been proposed.

[0003]

The above-mentioned PVD method and C
All CBN films synthesized by the VD method are formed directly on a substrate or an intermediate layer formed on the substrate, and a clear boundary is formed between the substrate or the intermediate layer and the film. Exists. Therefore, all of these CBN films have poor adhesion, and at present, films that can withstand practical use have not been formed yet. The reason why the adhesion of the CBN film becomes poor is that any of the manufacturing methods basically utilizes a non-equilibrium reaction, and the synthesized CBN film has a large internal stress, and the substrate or the intermediate layer may not have a large internal stress. This is because the adhesion at the boundary of the film cannot be withstand the internal stress and peels off. Another reason is that CBN itself is a substance having low reactivity, so that the adhesion to the substrate is smaller than that of other ceramic films. The present invention has been made in view of the above circumstances, and has as its object to provide a boron nitride-coated member having a CBN film with improved adhesion.

[0004]

Therefore, in the present invention, CB
As means for improving the adhesion of the N film, in a boron nitride coating member formed by forming a boron nitride film on a base material or an intermediate layer formed on the base material, A boundary layer, which is a mixed composition of the base material or the intermediate layer material and boron nitride, is formed at the boundary portion, and the composition of the boundary layer is gradually reduced from the base material or the intermediate layer component toward the coating side. The graded composition is used, and cubic boron nitride is present in the boundary layer, and the amount of the cubic boron nitride in the boundary layer is gradually reduced from the boron nitride film side to the base material or the intermediate layer side. It is.

[0005]

The reason why the adhesion is improved by forming a boundary layer having a gradient composition between the substrate or the intermediate layer and the CBN film is as follows. The reason why the adhesion of the CBN film is poor is that the internal stress of the film is large as described above. Therefore, by forming a boundary layer having a gradient composition, the composition and structure of the material are continuously changed, so that the internal stress of the film gradually shifts from the film side to the substrate side or the intermediate layer side. It becomes possible to go. In other words, by eliminating the boundary between the base material or the intermediate layer and the film, the internal stress of the film is not concentrated on the boundary, but is dispersed in the thickness of the boundary layer, thereby suppressing the peeling of the film due to the internal stress. it can. In addition, by including CBN in the boundary layer and sequentially reducing its abundance from the film side to the base material or the intermediate layer, structural bonding between the boundary layer and the film becomes possible. The mechanical strength is improved, and the adhesion between the two is further improved.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
As shown in FIG. 1, the boron nitride-coated member of the present embodiment has a substrate 1 made of high-speed tool steel (JIS standard: SKH51).
An intermediate layer 2 made of titanium nitride, a boundary layer 3 having a gradient composition, and a CBN layer 4 are sequentially formed thereon.

Here, as the intermediate layer 2, a titanium nitride film having a thickness of 3 μm was formed by, for example, ion plating by the HCD (holo cathode) method. Specifically, after performing pretreatment by ultrasonic cleaning with an organic solvent (for example, Freon), the substrate 1 is subjected to ion bombardment at, for example, 1 kv × 1 A in 0.1 Torr Ar for 10 minutes. It was formed by coating under the conditions of 45 V × 400 A, substrate temperature: 500 ° C., and reactive gas: N ₂ partial pressure of 5 × 10 ⁻⁴ Torr. Note that the intermediate layer does not necessarily need to be formed, and the same effect can be obtained even if the boundary layer 3 is formed directly on the base material 1.

Next, a method for producing the boundary layer 3 on the intermediate layer 2 or the substrate 1 will be described. There are various methods for forming the boundary layer, and among them, an ion implantation method, an ion beam mixing method, and the like are suitable. First, a manufacturing method by an ion implantation method is described. In this method, the ion accelerating voltage is 200 kv, the ion species are nitrogen and boron, and these ion species are each 8 × 10 ¹⁷ ions / cm ^2.
Is injected into the above-mentioned intermediate layer 2 or substrate 1. to this
Nitrogen and boron are embedded in the intermediate layer 2 or the base material 1
In fact, the amount of these sinks naturally decreases in the depth direction.
Accordingly, the composition of CBN naturally decreases in the depth direction,
Conversely, the boundary layer 3 having a gradient composition in which the components of the intermediate layer or the base material increase in the depth direction was formed.

Next, a manufacturing method by ion beam mixing will be described. This method is performed using an apparatus as shown in FIG. The apparatus shown in FIG. 1 is installed at the lower portion in the vacuum vessel 11 while irradiating nitrogen ions from the ion source 14 to the base material 13 attached to the upper substrate holder 12 in the vacuum vessel 11. The metal boron 16 in the evaporation source 15 is evaporated by the electron beam 17, and the boron vapor 18 is deposited on the substrate 13. Here, 19 is a monitor for measuring the amount of boron vapor 18 deposited on the substrate.

As a manufacturing procedure, first, the base material 1 having the intermediate layer 2 or only the base material 1 is set at the base material 13 and the inside of the vacuum vessel 11 is pre-evacuated to 2 × 10 ⁻⁶ Torr or less. Next, the nitrogen and the rare gas (for example, argon) supplied to the ion source 14 are ionized in the ion source 14, and the mixed ions 20 are irradiated to the base 13, and the evaporation source
5. Boron vapor 18 obtained by evaporating metallic boron 16 from
3 on top. At this time, the energy of the mixed ions 20 is reduced stepwise to 70 keV, 2 keV, and 1 keV,
The evaporation rate of the boron vapor 18 at that time was 3 ° / sec when the accelerating voltage was 70 keV, and 2 ° / sec when the accelerating voltage was 2 keV.
The boundary layer 3 containing CBN and having a graded composition was formed as shown in FIG. 1 by setting 1Å / sec at 1 keV and treating for 5 minutes each. Here, in order to include CBN in the boundary layer 3, it is necessary to change the accelerating voltage stepwise. In particular, a low accelerating voltage of 2 keV or 1 keV is important. At this time, the degree of vacuum is about 1 × 10 ⁻⁴ Torr.

The method for forming the CBN layer 4 on the boundary layer 3 is basically the same as the procedure for forming the boundary layer 3. Specifically, the irradiation energy of the mixed ions 20 is 0.5 keV, and the evaporation rate of the boron vapor 18 is 0.4 ° / sec.
As a result, the CBN layer 4 could be formed. Further, the CBN layer 4 can be formed on the boundary layer obtained by the ion implantation method in the same manner.

As a result of composition analysis in the depth direction of the boron nitride-coated member having titanium nitride as an intermediate layer manufactured by the above-described embodiment by Auger electron spectroscopy, the composition in the boundary layer 3 was changed from the film side to the intermediate position. The atomic ratio of boron continuously decreases toward the layer side, while the atomic ratio of titanium continuously increases,
It was confirmed that the boundary layer 3 had a gradient composition. Further, structural analysis of boron nitride was performed by photoelectron spectroscopy, and it was confirmed that CBN was present in the boundary layer 3.
FIG. 3 shows the results of evaluating the adhesion of the obtained boron nitride-coated member by a scratch test. When the boundary layer 3 is formed, it is 8 to 10 times larger than when the boundary layer 3 is not provided.
The adhesive force (the load at the time of peeling of the film in the scratch test) increased, indicating that it had excellent adhesiveness. For comparison, a boundary layer was formed by setting the irradiation energy of the mixed ions to only 70 keV, and then the CBN was formed.
When the film was synthesized, Auger electron spectroscopy analysis confirmed that the boundary layer had a gradient composition, but photoelectron spectroscopy analysis revealed that CBN was not present in the boundary layer. Further, as a result of evaluating the adhesion by a scratch test, as shown in FIG. 3, the adhesion is significantly improved as compared with the case where there is no boundary layer.
It is inferior to when BN is present. Thus, the effect of having CBN in the boundary layer was shown.

[0013]

As described above, the boron nitride-coated member according to the present invention has excellent adhesion as compared with conventional ones, and can be used not only for cutting tools but also for bearings of various rotating devices. It can withstand practical use as other wear-resistant members such as sliding members such as slides, and is of great industrial value.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a boron nitride coating member according to one embodiment of the present invention.

FIG. 2 is a schematic view of a boron nitride coating member forming apparatus according to one embodiment of the present invention.

FIG. 3 is a view showing a critical load obtained by performing a coating scratch test on the boron nitride-coated member according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Intermediate layer 3 Boundary layer 4 CBN layer 11 Vacuum container 12 Substrate holder 13 Substrate 14 Ion source 15 Evaporation source 16 Metal boron 17 Electron beam 18 Boron vapor 19 Monitor 20 Nitrogen + rare gas mixed ion

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuki Yamashita 1-8-cho, Koura-cho, Kanazawa-ku, Yokohama-shi, Kanagawa 1 In the Basic Technology Research Laboratory Mitsubishi Heavy Industries, Ltd. 8 Machime 1 Mitsubishi Heavy Industries, Ltd. Basic Technology Laboratory (56) References JP-A-2-236268 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C23C 14/00- 14/58 C23C 16/30 C23C 28/00

Claims (1)

(57) [Claims] 1. A boron nitride coating member comprising a base material or an intermediate layer formed on the base material and a boron nitride film formed on the base material or an intermediate layer formed on the base material. Forming a boundary layer that is a mixed composition of the intermediate layer material and boron nitride, and setting the composition of the boundary layer to a gradient composition in which the base material or the intermediate layer component is gradually reduced from the base material side to the coating side; A boron nitride coating, wherein cubic boron nitride is present in the boundary layer and the amount of the cubic boron nitride in the boundary layer is gradually reduced from the boron nitride film side to the substrate or the intermediate layer side. Element.